This invention relates to a ring binder mechanism having an actuating crank.
Many modern ring binder mechanisms have actuating levers for opening and closing two, three or more rings. In some such devices, the levers also lock the rings closed. The typical arrangement is to attach the bottoms of the ring halves to hinged plates confined between the edges of an arcuate metal housing which provides a toggling action as the plates snap between open and closed positions.
Other devices have been proposed in which the rings are opened and/or closed by a cam-type mechanism. Prior such constructions are seen in U.S. Pat. Nos. 778,910, 2,494,898, 2,789,561, and 2,894,513. U.S. Pat. No. 778,910 discloses a two-ring binder mechanism which is opened by lifting the end of a lever which depresses a crank whose ends are the movable ends of the two rings. U.S. Pat. No. 6,637,968 shows a device more closely related to the present invention.
In most ring binder mechanisms, the opposed ring parts are both semicircular, so that when they are closed, they form substantially a circular shape. One problem with semi-circular ring parts is that they do not make it easy to load or remove large numbers of papers at once onto or off of the rings. Automatic machine loading of papers onto such rings is particularly difficult. For this reason, some prior inventors have developed rings in which one segment is straight, or almost so. With such rings, commonly called D-rings, a large group of papers can be lowered right onto the straight segments very simply and quickly. But since D-rings are not symmetrical, the tips meet to the left or right of the center plane of the mechanism and therefore approach one another not axially, but rather with a lateral component so that the line of approach is oblique to the length of the straight segment. The greater the offset, the greater the lateral component.
An oblique approach direction creates difficulty when one tip has a protrusion designed to seat within in recess in the other. With this construction, an oblique approach may result in interference between the approaching tips, preventing or impeding proper seating. The solution to this problem, until now, has been to bend the tip of the straight segment inward so that it points at the approaching tip of the arcuate segment. Bending the tip, however, works against the goal of facilitating the installation and removal of large groups of papers.